This month’s (March) issue has two important papers describing the effects of general anesthetics on the developing brain. There is abundant evidence that exposure to general anesthetics results in apoptosis in developing brains, though the relevance of these findings to human practice is still hotly debated.
First, Istaphanous and colleagues
have made a substantial contribution by defining the MAC of commonly used volatile agents in mice, subsequently finding 6 hours of exposure of 0.6 MAC of sevoflurane, desflurane or isoflurane to all cause equivalent and clear apoptotic injury in a newborn rodent model.
To date, most studies have concentrated on the effect of anesthesia exposure to the newborn; however, it is well recognized that the period of vulnerability is very likely to extend into the period where the brain is developing in utero. Exploring the effect of anesthesia exposure on the developing fetal brain, Palaisamy and colleagues
demonstrated that rats exposed to 4 hours of 1.5% isoflurane in utero were behaviorally abnormal compared to adults. In an accompanying editorial, Pamela Flood
highlights the importance and limitations of this study. As is the case with similar studies of the newborn animal, there are several important limitations when seeking to translate the findings to humans; nevertheless, this study, like that of Istaphanous et al
, adds further to the growing body of evidence that anesthesia is not completely innocuous to the developing brain and much more research is needed, especially with regard to the specific clinical implications of this information.
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Posted by Andrew Davidson, MBBS MD FANZCA